December is a unique month in the birthstone calendar, offering not one, but four distinct gemstones to celebrate those born in its final days: Turquoise, Zircon, Tanzanite, and Blue Topaz. Each of these stones possesses its own unique history, geological origin, and set of gemological properties, yet they share a common chromatic theme of cool blues and greens that perfectly complement the winter season. This article delves into the rich tapestry of information surrounding these December birthstones, exploring their historical significance, geological formation, physical characteristics, and the cultural lore that has elevated them from simple minerals to cherished symbols of protection, wisdom, and tranquility. By examining the available sources, we can construct a detailed portrait of each gemstone, providing enthusiasts, collectors, and jewelry buyers with the expert knowledge needed to appreciate these remarkable treasures of the earth.
Historical Significance and Lore
The history of December's birthstones is as varied as the stones themselves, with Turquoise emerging as the oldest and most traditional of the group. Evidence of its use dates back thousands of years, with archaeological finds in ancient Egyptian tombs, including that of King Tutankhamun, showcasing turquoise-adorned jewelry and artifacts. This deep connection to royalty and antiquity establishes turquoise as a gemstone of enduring value. Its lore is rich with beliefs centered on protection and good fortune. From the 13th century onward, it was widely believed that turquoise could protect the wearer from falling, a belief so strong that the gem was often set into horse bridles. Hindu mystics held that seeing a turquoise after observing the new moon would ensure fantastic wealth. Furthermore, the stone was thought to possess the power to break into several pieces at the approach of disaster, acting as a tangible warning of impending danger.
Turquoise also played a pivotal role in the spiritual and cultural lives of Native American tribes. The Apache believed that turquoise could be found by following a rainbow to its end, linking the stone to celestial phenomena and hope. Across various cultures, turquoise has been associated with wisdom, tranquility, friendship, and the promotion of positive energy. Its significance is so profound that it is often considered a talisman for enhancing communication and fostering harmonious relationships.
While turquoise holds the title of the most ancient December birthstone, the other gems have their own historical narratives. Zircon, for instance, is one of the oldest minerals on Earth, with some specimens dating back billions of years. Although not as prominently featured in the historical lore of December specifically, its use in jewelry spans centuries. Tanzanite is a more recent addition to the gemological world, discovered in the 20th century, but its rapid rise to fame has been fueled by its unique color and limited geographic origin. Blue Topaz, while historically available in pale shades, has become a popular modern birthstone due to treatments that enhance its color to a deep, vivid blue. The collective history of these stones reflects humanity's long-standing fascination with gems that capture the essence of the sky and sea, offering a symbolic connection to the natural world.
Geological Formation and Sources
The origins of December's birthstones are as diverse as their histories, each forming under distinct geological conditions and sourced from specific regions around the globe.
Turquoise is a hydrous phosphate of copper and aluminum. Its formation requires a unique combination of geological events: the weathering of pre-existing rocks containing copper, aluminum, and phosphorus, followed by the infiltration of water carrying these dissolved elements. The presence of copper is responsible for the blue color, while iron impurities can create green hues. Turquoise is primarily mined in arid regions where specific weather conditions facilitate its formation. Significant sources include the southwestern United States (notably Arizona, Nevada, and New Mexico), Iran (home of the highly prized Persian turquoise, known for its vivid sky-blue color and minimal matrix), Egypt, China, Mexico, and parts of Central Asia and Africa. The matrix—the remnants of the host rock in which the turquoise formed—often appears as intricate veins or spiderwebs, adding to the stone's unique character.
Zircon is a zirconium silicate (ZrSiO₄) and is one of the oldest minerals on Earth, with some zircon crystals found in Australia dating back over 4.4 billion years. It forms in igneous and metamorphic rocks. While natural zircon occurs in a variety of colors, the blue variety is particularly associated with December. Blue zircon is typically heat-treated from brownish zircon crystals to achieve its desirable blue hue. Major sources for gem-quality zircon include Cambodia, Myanmar, Sri Lanka, and Australia. The stone's high refractive index gives it exceptional brilliance, often compared to that of diamond.
Tanzanite is a relatively new gemstone, discovered in the Merelani Hills of Tanzania in 1967. It is a variety of the mineral zoisite, specifically the blue to violet-blue variety caused by the presence of vanadium and other trace elements. The formation of tanzanite is linked to a unique geological event: the metamorphism of rocks during the formation of the East African Rift. This specific geological setting is believed to be the only source of gem-quality tanzanite in the world, making it significantly rarer than diamond. The stone is typically found in small, flat crystals and is almost always heat-treated to enhance its blue color from a naturally brownish or greenish hue.
Blue Topaz is a silicate mineral with the chemical formula Al₂SiO₄(F,OH)₂. While natural blue topaz occurs in pale shades, the deep, saturated blues seen in the market are almost always the result of irradiation treatment followed by heating. Topaz forms in igneous rocks, particularly in pegmatites and high-temperature veins. Major sources include Brazil, Nigeria, Sri Lanka, and Mexico. The United States, specifically Texas, has also been a historical source for blue topaz, though production there is limited. The treatment process is a well-established and accepted industry practice, making vibrant blue topaz accessible and affordable.
Gemological Properties
Understanding the physical and optical properties of these gemstones is crucial for their identification, valuation, and care. The following table summarizes key gemological characteristics based on the provided sources.
| Gemstone | Chemical Composition | Hardness (Mohs) | Crystal System | Typical Color | Special Properties |
|---|---|---|---|---|---|
| Turquoise | Hydrous phosphate of copper & aluminum | 5 - 6 | Triclinic | Blue to green, often with matrix | Opaque to semi-translucent; can be waxy to the touch. |
| Zircon | Zirconium silicate (ZrSiO₄) | 6.5 - 7.5 | Tetragonal | Colorless, blue, brown, yellow | High refractive index (brilliant); heat-sensitive; may undergo metamictization. |
| Tanzanite | Calcium aluminum silicate (Ca₂Al₃(SiO₄)₃(OH)) | 6.5 - 7 | Orthorhombic | Blue to violet-blue | Pleochroic (shows different colors from different angles); typically heat-treated. |
| Blue Topaz | Aluminum silicate with fluorine/hydroxyl | 8 | Orthorhombic | Pale blue to deep, vivid blue | Typically treated (irradiation & heat); very durable for jewelry. |
Turquoise has a relatively low hardness, ranging from 5 to 6 on the Mohs scale. This makes it susceptible to scratching and chipping, necessitating careful handling. Its composition and structure contribute to its porosity, which can affect its color stability and require specific cleaning methods.
Zircon is notably harder, with a Mohs hardness of 6.5 to 7.5, making it more durable for everyday wear than turquoise. However, zircon is known for its high refractive index and strong dispersion (fire), which gives it exceptional brilliance and sparkle, rivaling that of diamond. It is important to note that zircon can be heat-sensitive; sudden temperature changes can cause fracturing. Over geological time, some zircon crystals can become metamict (amorphous) due to the decay of radioactive elements, which can affect their clarity.
Tanzanite has a hardness of 6.5 to 7, placing it in the moderate durability range. Its most notable optical property is strong trichroism, meaning it can display three different colors—typically blue, violet, and burgundy—depending on the viewing angle. This characteristic requires skilled cutting to orient the stone for the most desirable blue hue. The vast majority of tanzanite on the market has been heat-treated to remove brownish tones and enhance its blue color, a stable and permanent process.
Blue Topaz is one of the hardest of the group, with a Mohs hardness of 8. This exceptional durability, combined with its affordability and vibrant color (when treated), makes it a popular choice for a wide range of jewelry. The deep blue color of commercial blue topaz is achieved through a combination of irradiation and heat treatment. Irradiation creates color centers, and subsequent heating stabilizes the color. This process is considered permanent under normal wearing conditions.
Symbolism and Metaphysical Beliefs
The symbolic meanings attributed to these gemstones are deeply rooted in history and cultural traditions, often overlapping in themes of protection, health, and spiritual well-being.
Turquoise is universally regarded as a stone of protection, wisdom, and tranquility. Its lore across various cultures—from ancient Egypt to Native American tribes—emphasizes its role as a guardian against negative energies, physical harm (such as falls), and misfortune. It is also believed to promote clear communication, foster friendship, and bring peace and happiness to the wearer. The Apache belief linking turquoise to the rainbow underscores its connection to hope and celestial guidance.
Zircon, while not as prominently featured in historical metaphysical lore within the provided sources, has been associated with purity, clarity, and prosperity. Its brilliant sparkle is often linked to the ability to attract wealth and success. In some traditions, zircon is believed to aid in sleep and promote spiritual grounding.
Tanzanite, as a modern discovery, has quickly accumulated its own set of symbolic meanings. It is often associated with transformation, intuition, and spiritual awakening. Its unique trichroic nature is seen as a metaphor for seeing situations from multiple perspectives. Some believe that tanzanite can stimulate the throat and third eye chakras, enhancing communication and psychic abilities.
Blue Topaz is widely associated with calm, clarity, and emotional balance. It is believed to soothe the mind, reduce stress, and promote honest communication. Its deep blue color is linked to the throat chakra, making it a popular stone for those seeking to express themselves more clearly and confidently. In some beliefs, blue topaz is also associated with love and affection.
Care and Cleaning
Proper care is essential to maintain the beauty and longevity of any gemstone. The durability of December's birthstones varies significantly, requiring tailored maintenance approaches.
Turquoise, with its hardness of 5-6 and porosity, is the most delicate of the group. It should be protected from harsh chemicals, perfumes, and cosmetics, which can damage its surface and alter its color. Cleaning should be done with a soft, dry cloth. Avoid ultrasonic cleaners, steam cleaners, and prolonged exposure to water, as these can cause cracking or discoloration. It is best to remove turquoise jewelry before engaging in physical activities or household chores.
Zircon is relatively durable but requires caution due to its potential for fracture and its sensitivity to heat. Avoid sudden temperature changes and harsh impacts. Cleaning can be done with warm, soapy water and a soft brush. Ultrasonic cleaners are generally safe for zircon, but it is advisable to avoid them if the stone has visible inclusions or fractures. Steam cleaning is not recommended.
Tanzanite has moderate hardness (6.5-7) but can be prone to chipping if struck. It is also sensitive to heat and pressure. Cleaning with warm, soapy water and a soft brush is safe. Ultrasonic cleaners and steam cleaners should be avoided, as they can cause damage, especially if the stone has fractures. It is important to handle tanzanite jewelry with care to prevent impact damage.
Blue Topaz, with its high hardness of 8, is very durable and resistant to scratching. It can be cleaned safely with warm, soapy water and a soft brush. Ultrasonic cleaners are generally safe for blue topaz, but caution is advised if the stone has inclusions or fractures. Steam cleaning is also typically safe. However, it is important to note that the irradiation treatment used to color some blue topaz is permanent, but extreme heat could potentially alter the color, so it is best to avoid exposing blue topaz jewelry to high temperatures.
Conclusion
The four birthstones of December—Turquoise, Zircon, Tanzanite, and Blue Topaz—offer a remarkable spectrum of color, history, and meaning. From the ancient, protective turquoise cherished by royalty and indigenous cultures to the brilliant, ancient zircon and the modern, transformative tanzanite, each stone tells a unique story. Blue topaz, with its exceptional durability and vibrant treated color, provides an accessible and beautiful option. Together, they form a cohesive group that captures the cool, serene palette of winter. Whether chosen for their historical significance, geological rarity, or metaphysical properties, these gemstones provide a wealth of options for those born in December, allowing for personal expression and a connection to the enduring beauty of the mineral kingdom. Their distinct characteristics, from hardness to lore, ensure that there is a perfect December birthstone for every preference and purpose.